This disclosure relates to electrical generators, and more particularly to electrical generators having bearings for supporting a rotor shaft.
In electrical generators, such as those used to power electrical systems of aircraft, the electrical generator is connected to the main engine of the aircraft by a drive shaft. The drive shaft is connected to a rotor assembly of the electrical generator through a rotor shaft. The rotor assembly is mounted on the rotor shaft and rotates within a stator assembly. The rotor shaft is supported for rotation in a generator housing using bearing assemblies.
The drive end of a known electrical generator includes a main bearing that floats axially in a liner bore of a bearing liner to accommodate differential thermal expansion and contraction. The floating main bearing fit in the liner bore is typically 0.076 mm (0.0003 inches) tight to 0.076 mm (0.0003 inches) loose for room temperature conditions. Because the bearing liner is made from aluminum and the outer ring of the main bearing is made from steel, clearances increase at operational temperatures. When a loose fit exists and operational vibration is present, there is a potential for fretting corrosion, which can result in a potential to restrict the axial motion of the main bearing in the bearing liner.